internal/clientinfo: use jaytaylor/go-hostsfile for parsing hosts file

txn2/txeh lower the hostname, which is not suitable for ctrld use case.

go.mod

@@ -12,6 +12,7 @@ require (
 	github.com/hashicorp/golang-lru/v2 v2.0.1
 	github.com/illarion/gonotify v1.0.1
 	github.com/insomniacslk/dhcp v0.0.0-20230407062729-974c6f05fe16
+	github.com/jaytaylor/go-hostsfile v0.0.0-20220426042432-61485ac1fa6c
 	github.com/josharian/native v1.1.1-0.20230202152459-5c7d0dd6ab86
 	github.com/kardianos/service v1.2.1
 	github.com/miekg/dns v1.1.55
@@ -23,9 +24,7 @@ require (
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.16.0
 	github.com/stretchr/testify v1.8.3
-	github.com/txn2/txeh v1.5.3
 	github.com/vishvananda/netlink v1.2.1-beta.2
-	go4.org/mem v0.0.0-20220726221520-4f986261bf13
 	golang.org/x/net v0.10.0
 	golang.org/x/sync v0.2.0
 	golang.org/x/sys v0.8.1-0.20230609144347-5059a07aa46a
@@ -70,6 +69,7 @@ require (
 	github.com/subosito/gotenv v1.4.2 // indirect
 	github.com/u-root/uio v0.0.0-20230305220412-3e8cd9d6bf63 // indirect
 	github.com/vishvananda/netns v0.0.4 // indirect
+	go4.org/mem v0.0.0-20220726221520-4f986261bf13 // indirect
 	golang.org/x/crypto v0.9.0 // indirect
 	golang.org/x/exp v0.0.0-20230425010034-47ecfdc1ba53 // indirect
 	golang.org/x/mod v0.10.0 // indirect

go.sum

@@ -163,6 +163,8 @@ github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/insomniacslk/dhcp v0.0.0-20230407062729-974c6f05fe16 h1:+aAGyK41KRn8jbF2Q7PLL0Sxwg6dShGcQSeCC7nZQ8E=
 github.com/insomniacslk/dhcp v0.0.0-20230407062729-974c6f05fe16/go.mod h1:IKrnDWs3/Mqq5n0lI+RxA2sB7MvN/vbMBP3ehXg65UI=
+github.com/jaytaylor/go-hostsfile v0.0.0-20220426042432-61485ac1fa6c h1:kbTQ8oGf+BVFvt/fM+ECI+NbZDCqoi0vtZTfB2p2hrI=
+github.com/jaytaylor/go-hostsfile v0.0.0-20220426042432-61485ac1fa6c/go.mod h1:k6+89xKz7BSMJ+DzIerBdtpEUeTlBMugO/hcVSzahog=
 github.com/josharian/native v1.0.1-0.20221213033349-c1e37c09b531/go.mod h1:7X/raswPFr05uY3HiLlYeyQntB6OO7E/d2Cu7qoaN2w=
 github.com/josharian/native v1.1.1-0.20230202152459-5c7d0dd6ab86 h1:elKwZS1OcdQ0WwEDBeqxKwb7WB62QX8bvZ/FJnVXIfk=
 github.com/josharian/native v1.1.1-0.20230202152459-5c7d0dd6ab86/go.mod h1:aFAMtuldEgx/4q7iSGazk22+IcgvtiC+HIimFO9XlS8=
@@ -270,8 +272,6 @@ github.com/stretchr/testify v1.8.3 h1:RP3t2pwF7cMEbC1dqtB6poj3niw/9gnV4Cjg5oW5gt
 github.com/stretchr/testify v1.8.3/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/subosito/gotenv v1.4.2 h1:X1TuBLAMDFbaTAChgCBLu3DU3UPyELpnF2jjJ2cz/S8=
 github.com/subosito/gotenv v1.4.2/go.mod h1:ayKnFf/c6rvx/2iiLrJUk1e6plDbT3edrFNGqEflhK0=
-github.com/txn2/txeh v1.5.3 h1:ZMgc3r+5/AFtE/ayCoICpvxj7xl/CYsZjnIGhozV/Kc=
-github.com/txn2/txeh v1.5.3/go.mod h1:qYzGG9kCzeVEI12geK4IlanHWY8X4uy/I3NcW7mk8g4=
 github.com/u-root/uio v0.0.0-20230305220412-3e8cd9d6bf63 h1:YcojQL98T/OO+rybuzn2+5KrD5dBwXIvYBvQ2cD3Avg=
 github.com/u-root/uio v0.0.0-20230305220412-3e8cd9d6bf63/go.mod h1:eLL9Nub3yfAho7qB0MzZizFhTU2QkLeoVsWdHtDW264=
 github.com/vishvananda/netlink v1.2.1-beta.2 h1:Llsql0lnQEbHj0I1OuKyp8otXp0r3q0mPkuhwHfStVs=

internal/clientinfo/hostsfile.go

@@ -2,40 +2,51 @@ package clientinfo
 
 import (
 	"os"
+	"sync"
 
 	"github.com/fsnotify/fsnotify"
-	"github.com/txn2/txeh"
+	"github.com/jaytaylor/go-hostsfile"
 
 	"github.com/Control-D-Inc/ctrld"
 )
 
 // hostsFile provides client discovery functionality using system hosts file.
 type hostsFile struct {
-	h       *txeh.Hosts
 	watcher *fsnotify.Watcher
+	mu      sync.Mutex
+	m       map[string][]string
 }
 
 // init performs initialization works, which is necessary before hostsFile can be fully operated.
 func (hf *hostsFile) init() error {
-	h, err := txeh.NewHostsDefault()
-	if err != nil {
-		return err
-	}
-	hf.h = h
 	watcher, err := fsnotify.NewWatcher()
 	if err != nil {
 		return err
 	}
 	hf.watcher = watcher
-	if err := hf.watcher.Add(hf.h.ReadFilePath); err != nil {
+	if err := hf.watcher.Add(hostsfile.HostsPath); err != nil {
 		return err
 	}
+	m, err := hostsfile.ParseHosts(hostsfile.ReadHostsFile())
+	if err != nil {
+		return err
+	}
+	hf.mu.Lock()
+	hf.m = m
+	hf.mu.Unlock()
 	return nil
 }
 
 // refresh reloads hosts file entries.
 func (hf *hostsFile) refresh() error {
-	return hf.h.Reload()
+	m, err := hostsfile.ParseHosts(hostsfile.ReadHostsFile())
+	if err != nil {
+		return err
+	}
+	hf.mu.Lock()
+	hf.m = m
+	hf.mu.Unlock()
+	return nil
 }
 
 // watchChanges watches and updates hosts file data if any changes happens.
@@ -66,11 +77,10 @@ func (hf *hostsFile) watchChanges() {
 
 // LookupHostnameByIP returns hostname for given IP from current hosts file entries.
 func (hf *hostsFile) LookupHostnameByIP(ip string) string {
-	hf.h.Lock()
-	defer hf.h.Unlock()
-
-	if names := hf.h.ListHostsByIP(ip); len(names) > 0 {
-		return names[0]
+	hf.mu.Lock()
+	defer hf.mu.Unlock()
+	if names := hf.m[ip]; len(names) > 0 {
+		return normalizeHostname(names[0])
 	}
 	return ""
 }